365 research outputs found
Impact of Realistic Propagation Conditions on Reciprocity-Based Secret-Key Capacity
Secret-key generation exploiting the channel reciprocity between two
legitimate parties is an interesting alternative solution to cryptographic
primitives for key distribution in wireless systems as it does not rely on an
access infrastructure and provides information-theoretic security. The large
majority of works in the literature generally assumes that the eavesdropper
gets no side information about the key from her observations provided that (i)
it is spaced more than a wavelength away from a legitimate party and (ii) the
channel is rich enough in scattering. In this paper, we show that this
condition is not always verified in practice and we analyze the secret-key
capacity under realistic propagation conditions
Collisions of uniformly distributed identifiers with an application to MAC address anonymization
The main contribution of this paper consists in theoretical approximations of
the collision rate of random identifiers uniformly distributed in
buckets---along with bounds on the approximation errors. A secondary
contribution is a decentralized anonymization system of media access control
(MAC) addresses with a low collision rate. The main contribution supports the
secondary one in that it quantifies its collision rate, thereby allowing
designers to minimize while attaining specific collision rates. Recent
works in crowd monitoring based on WiFi probe requests, for which collected MAC
addresses should be anonymized, have inspired this research
Analytical Creeping Wave Model and Measurements for 60 GHz Body Area Networks
International audienceThe propagation of 60 GHz electromagnetic waves around a human body is studied analytically and experimentally. The body is treated here as a circular lossy cylinder, which is an approximation of the human torso. Analytical formulations based on creeping wave theory are given and discussed for both vertical and horizontal polarizations. An exact path gain expression is derived from analytical formulations and a simpler first order approximation is given. Path gain coefficients are shown for frequencies spanning the world available 60 GHz unlicensed band and for several sizes of the torso. Finally, the results of an experimental campaign conducted in an anechoic chamber to isolate the contribution of on-body propagation are reported. The measurement of the distance dependence of the received power on a brass cylinder and on a human body for both vertical and horizontal polarizations confirmed theoretical predictions
Millington Effect and Propagation Enhancement in 60-GHz Body Area Networks
International audienceMillington effect for on-body propagation enhancement is presented in the 60-GHz band. Millington’s equations are developed to describe propagation above a flat inhomogeneous surface. This study focuses on mixed paths (human skin - metallic) for on-body scenarios. It is shown that adding metallic paths on the human skin can improve the power link budget between two nodes placed on the body. Two different schemes are studied experimentally to assess the analytical model using a flat phantom with electric properties of human skin and different lengths of metallic inserts. The first scheme considers a metallic plate between the transmitting and receiving antennas, while the second scheme proposes locating the metallic plates under the antennas. It is shown that the second scheme yields a better link budget than the first one for the same length of metal. Moreover, a numerical study is performed to assess the impact of the following different parameters: the location of the metal plate, size of the plate and the height of the antennas. Excellent agreement between numerical and experimental results has been shown. In the best cases, the presented techniques allow to improve the path loss of 10 to 20 dB
Angle-of-Arrival based localization using polynomial chaos expansions
International audienceIn this paper, polynomial chaos expansions are applied to angle-of-arrival based localization. By using a polynomial chaos expansion on a least squares estimator, a new positioning method is designed. Simulation results show that the proposed method returns precise information about the statistical distribution of the position
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